{"schema_version":"secwatch.filing_event.v1","accession":"0002022626-25-000005","form_type":"8-K","ticker":"UPB","cik":"0002022626","company_name":"Upstream Bio, Inc.","filed_at":"2025-09-02T23:59:59+00:00","discovered_at":"2026-05-14T18:02:45.846914+00:00","generated_at":"2026-05-17T09:01:45.715618+00:00","sec_items":["7.01","8.01","9.01"],"event_type":"other_material","sentiment":"positive","materiality_score":0.78,"calibrated_materiality_score":0.78,"confidence":"high","headline":"Upstream Bio Phase 2 VIBRANT trial meets primary endpoint for verekitug in CRSwNP","bullets":["Placebo-adjusted reduction in nasal polyp score of -1.8 (p<0.0001) at Week 24; key secondary endpoint nasal congestion score reduced -0.8 (p=0.0003).","76% reduction in need for surgery or systemic corticosteroids (p=0.03); no serious adverse events observed.","Verekitug (100 mg every 12 weeks) generally well tolerated; company plans to engage regulators and present at upcoming medical conference.","Additional top-line data for verekitug in severe asthma expected in coming months."],"urls":{"canonical":"https://secwatch.observer/filing/0002022626-25-000005","json":"https://secwatch.observer/filing/0002022626-25-000005.json","markdown":"https://secwatch.observer/filing/0002022626-25-000005.md","text":"https://secwatch.observer/filing/0002022626-25-000005.txt","edgar_index":"https://www.sec.gov/Archives/edgar/data/2022626/000202262625000005/0002022626-25-000005-index.htm","edgar_primary_document":"https://www.sec.gov/Archives/edgar/data/2022626/000202262625000005/upb-20250902.htm"},"model":{"generated_by":"deepseek-v4-flash:cloud@v2","generated_at":"2026-05-17T09:01:45.715618+00:00"},"review":{"review_status":"machine_generated","human_reviewed":false,"corrected":false,"correction_note":null,"correction_timestamp":null,"superseded_by":null,"related_filings":[]},"source_grounded_claims":[],"license":"Source filings: public domain (SEC EDGAR). Summaries (headline + bullets): CC-BY-4.0; attribute https://secwatch.observer"}